Price Comparisons
Pharmaceutical Sales
AIDS Drugs
Lunesta, Ambien, Sonata Rozerem

Arthritis Drugs
Atypical Antipsychotics
Cholesterol Drugs
Diabetes Drugs
Diabetic Supplies
Drug Information Databases
Osteoporosis Drugs
Ortho Evra Lawsuit
Pharmaceutical Sales
Pharmacy CE
Vioxx Trial
Whistleblower Law
Zyprexa Lawsuit
Antibiotics without a prescription
SEARCH Medline
Medline Plus  by Topic
New Drugs (Center Watch)
Gen Info;Site Dissection
Boiler Plate Patient Info
Advisory Documents
Drugs@FDA [gateway]
Drug Approvals Report

Newly filed ANDA's
Product Data Database
Orange Book
Upcoming Meetings

Medwatch Safety

Warning Letters

Medical Abbreviations
Search By Abbreviation
Search By Definition

Internet Drug News'

Antihistamine Database 
Internet Drug News 
Explanation of how antihistamines work, side effects, antidotes, etc.


Allegra (Fexofenadine; Sanofi Aventis) Prescription ONLY
Prescribing Info Source A | Prescribing Information Source B
Official Website - patient oriented; explains allergies
General Information
Medline Search
Compare Prices

Allegra D = Allegra + Decongestant combination tablet; Aventis
Allegra D 12-hr prescribing Info | Allegra D 24-hr prescribing info
Allegra D 12 -hr general information
Allegra D 24-hr general information
Official Website; patient oriented; allergy resources
Compare prices

Astelin (Azelastine Hydrochloride)  prescription antihistamine in nasal spray form;
Prescribing Information - Official website; very nicely done
General Information
Medline Search
Google Search

Clarinex (Desloratadine; Schering-Plough) Prescription ONLY
Prescribing Information - PDF File; takes a minute to load - Official website; very nicely done
General Information
Picture Of Clarinex Pill
Medline Search
Google Search
Compare prices

Clarinex D 12 hour (Desloratadine + decongestant in the same tablet; Schering-Plough) Prescription ONLY
Prescribing information
General information
Patient Information

Clarinex D 24 Hour
(Desloratadine + decongestant in the same tablet; Schering-Plough)
Prescription ONLY
Prescribing information
General information

Claritin (Loratidine; Schering-Plough)
Available Over The Counter as of 12/02

Prescribing Info 
Official Website -
General Information
Medline Search

Claritin D = Claritin + decongestant combination tablet; Schering Plough
12 hr: Prescribing Info  | General Information
24 hr :Prescribing Info Source  | General Information

Diphenhydramine (Benadryl) Over-The-Counter
Patient Information
General Information
Prescribing Information

Palgic (carbinoxamine maleate) Pamlab
Patient Information
General Information
Prescribing Information

SOLTARA (tecastemizole Sepracor)
Soltara was (is) a metabolite of astemizole (HISMANAL®, Johnson
& Johnson), a nonsedating antihistamine that was withdrawn from the
US Market in 1999 due to safety concerns
FDA said that Soltara was not approvable as of 3/02
Sepracor drops Soltara drug; newspaper article 12/2003
Scientific papers on Soltare (tecastemizole)

Xyzal (Levocetirizine UCB)
Prescribing Info
Official Website
General Information
Medline Search
Compare Prices

Zyrtec-Cetirizine - No Prescription Needed
Prescribing Info
Official Website - patient oriented; explains allergies; how Zyrtec helps.
General Information
Patient Information
Medline Search
Official Website - patient oriented; explains allergies; how Zyrtec helps.
Compare Prices

Zyrtec D = Zyrtec + decongestant combination tablet; UCB/Pfizer
Prescribing Info
Patient Information
General Information
Official Website - patient oriented; explains allergies; how Zyrtec helps.
Compare prices

Antihistamines are interesting compounds.  Structurally, classical
antihistamines resemble local anesthetics such as benzocaine or

How Do Antihistamines work?

Antihistamines are the antidote to exposure to histamine.  As their name
implies, antihistamines are able to block the effects of histamine in your
body.  [You should think of antihistamines as being the bouncer at
a club].

When histamine molecules get onto the surface of the cell, they cause
inflammation and irritation.   

Antihistamines displace the histamine molecules from the cell and form
a protective shield around the cells so that histamine can not interact
with the cell to cause an allergic reaction.


Let's say that you are allergic to the perfume in a lotion, but you get
some on your skin by accident.  You break out in an itchy rash where
the lotion touched your skin. 

What is happening is that the perfume in the lotion caused the cells in
your body to release histamine.  The histamine gets onto the surface
of your skin cells and causes an itchy rash. What do you do?

You take a dose of antihistamine such as Benadryl (diphenhydramine)
or Allegra (fexofenidine).  The antihistamine acts like a bouncer.  It kicks
the histamine off of the skin cells and prevents the histamine from
reacting to cause inflammation, redness and itch.

Within minutes the rash should subside and the itching go away.

What is histamine and why is it bad?

When you get an allergic reaction, a cascade of events takes place in
your body that results in the release of a substance know as
" histamine" .  You can think of histamine as being the " bad guy" in
an allergic reaction.

Histamine causes inflammation.  Histamine is very irritating to the body.
If you injected a tiny bit of pure histamine into your skin, the result is
that you would likely see a welt or a rash. 

When you are exposed to something that you are allergic to, the resulting
release of histamine can cause in an itchy rash, a welt, itchy eyes,
watery eyes, a runny nose, etc.

There is a severe, life threatening form of allergic reaction known as
anaphylactic shock. 

For instance, if you are highly allergic to  something like peanuts or
enicillin, and you are exposed to this thing that you are allergic to,
your body can react severely.

Your tongue and throat may swell up, you may experience a severe
rash all over your body and you may go into shock.

Side Effects

The most common side effect of antihistamines is drowsiness.  In fact,
drug companies often use antihistamines ( such as
or Benadryl
) as an over-the-counter sleeping pill.   

However, the early 1990's, scientists developed antihistamines (Allegra,
Claritin) that did not cause drowsiness at the recommended doses. 
These drugs are expensive and were available by prescription only at first. 

Zyrtec is another relatively recent antihistamine, but it is known to
cause more drowsiness than Claritin or Allegra.  That is why your
druggist may attach a drowsiness warning label to your bottle of Zyrtec.

Other Uses Of Antihistamines

The other main use of antihistamines is to cause sleepiness. 

Drug makers add a small amount of antihistamine (usually 25 mg or 50
mg of diphenhydramine, the active ingredient in Benadryl) to pain
killers and call the resulting concoction the "PM" version of the drug.

For example, Tylenol PM is simply tylenol with  a pinch of antihistamine
added to induce sleepiness.  Midol PM is Midol with a pinch of
antihistamine added to cause drowsiness.

There is also Excedrin PM, Anacin PM, Legatrin PM, etc.

Editors' Suggestions:

You may be interested in visiting:

American Academy Of Family Practice Physicians report regarding
antihistamines: description of, warnings, etc.

Antihistamines, Decongestants, and Analgesics (Systemic) -- Mayo Clinic;
list of, description, doses of, etc.

ENT Information

News Related to Allergies - (from Google)

Drug Information Database Page

Note To Visitors:

We never answer drug or health related questions so please don't e-mail us with your drug related questions.

If you have a question about a drug that you are taking or if you think you are experiencing a side effect from a drug that you are taking you must get in touch with the doctor who prescribed the drug or the pharmacist who dispensed it to you,
not us.

The information contained on this web site is for your information only.  You should never take a drug without a doctor's prescription.   Do NOT give yourself any drug unless it has been prescribed for you by a doctor.

It's foolish to start taking a medicine or stop taking a medicine on your own based on information you read here or any other internet web site because this could cause you to become seriously ill or die or worse even.

Questions or feedback regarding this site?  Contact Webmaster

Read Our Plain-English Privacy Policy

Copyright, 2008 Internet Drug News Inc - all rights reserved and Pharmaceutical News Harvest are registered Trademarks of Internet Drug News Inc.

We subscribe to The HONcode of  online conduct:

1.  Qualification of author(s)
This site is published and webmastered by Corey Nahman, Registered pharmacist in the Sate of New York.
Let it be known that the information provided on this site is designed to support, not replace, the relationship that exists between a patient/site visitor and his/her existing physician.
We respect the privacy of the users of this site.  Please see our plain English privacy policy.
At all times, the information on this site shall be footnoted with the source(s) of published information, date and medical and health pages provided.
This site shall at all times back up claims relating to benefits and performance.
This site shall at all times use accessible presentation, you can e-mail the publisher of this site at his personal e-mail address at any time.
Financial disclosure
This site is supported by click advertisements, banner advertisements and affiliate arrangements.  All ads are properly labeled as such.  If you have any questions regarding how we make money please e-mail the webmaster with your questions.  All advertisements shall be clearly distinguished from content.

Proudly Published In NEW YORK CITY, USA

Site Map |
Privacy Policy | Contact Webmaster |
Site Mission Statement, Intended Audience, Editorial Policy, Advertising Policy
This Page Last Updated 9/9/2008